import React from 'react'
import "./index.css"
export default function Footer({todoList , setTodoList}) {
   //计算已完成的个数
   const completed = () => {
    return todoList.reduce((p, c) => c.done ? p + 1 : p, 0);
  }
  // 全选逻辑
  const selectAll = (e) => {
    const expChecked = e.target.checked;

    const newTodoList = todoList.map((item) => {
      return { ...item, done: expChecked }
    })
    setTodoList(newTodoList)
  }
  return (
    <div className="todo-footer">
      <label>
        <input type="checkbox"onChange={selectAll} checked={completed() === todoList.length && todoList.length !== 0} />
      </label>
      <span>
        <span>已完成{completed()}</span> / 全部{todoList.length}
      </span>
      <button className="btn btn-danger" onClick={()=>{setTodoList(todoList.filter(item => !item.done))}}>清除已完成任务</button>
    </div>
  )
}
